Author: hiren Date: Mon Nov 21 20:53:11 2016 New Revision: 308943 URL: https://svnweb.freebsd.org/changeset/base/308943
Log: For RTT calculations mid-session, we explicitly ignore ACKs with tsecr of 0 as many borken middle-boxes tend to do that. But during 3whs, in syncache_expand(), we don't do that which causes us to send a RST to such a client. Relax this constraint by only using tsecr to compare against timestamp that we sent when it is not 0. As a result, we'd now accept the final ACK of 3whs with tsecr of 0. Reviewed by: jtl, gnn Sponsored by: Limelight Networks Differential Revision: https://reviews.freebsd.org/D8552 Modified: head/sys/netinet/tcp_syncache.c Modified: head/sys/netinet/tcp_syncache.c ============================================================================== --- head/sys/netinet/tcp_syncache.c Mon Nov 21 19:47:37 2016 (r308942) +++ head/sys/netinet/tcp_syncache.c Mon Nov 21 20:53:11 2016 (r308943) @@ -1069,10 +1069,17 @@ syncache_expand(struct in_conninfo *inc, } /* - * If timestamps were negotiated the reflected timestamp - * must be equal to what we actually sent in the SYN|ACK. + * If timestamps were negotiated, the reflected timestamp + * must be equal to what we actually sent in the SYN|ACK + * except in the case of 0. Some boxes are known for sending + * broken timestamp replies during the 3whs (and potentially + * during the connection also). + * + * Accept the final ACK of 3whs with reflected timestamp of 0 + * instead of sending a RST and deleting the syncache entry. */ - if ((to->to_flags & TOF_TS) && to->to_tsecr != sc->sc_ts) { + if ((to->to_flags & TOF_TS) && to->to_tsecr && + to->to_tsecr != sc->sc_ts) { if ((s = tcp_log_addrs(inc, th, NULL, NULL))) log(LOG_DEBUG, "%s; %s: TSECR %u != TS %u, " "segment rejected\n", _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
